Why nonce adjustment can guarantee leading zeros?

Any expert on sha256? Basically we are trying different {data}+nonce to find the nonce which would give expected leading zeros, seems regardless of the data, such nonce always exists? Is there any document i can refer to for such proof?

Thanks

Submitted January 03, 2022 at 08:29AM by UniqueAd1423 https://bit.ly/3FQgNyj